Gun sight

ABSTRACT

A sight assembly for mounting to a weapon. A holographic optical element and a light source are in a fixed angular configuration with respect to one another, but may be adjusted either together or individually in a horizontal or vertical direction. The sight assembly may have a mirror or lens. An adjustment mechanism is provided where a shaft includes at least two portions wherein the two portions of the shaft of the screw have different pitch directions and/or pitch dimensions allowing for slight adjustment the assembly. The light source may be a vertical-cavity surface emitting laser (VCSEL). A temperature sensor may sense a temperature of the VCSEL. A current to the VCSEL may be adjusted based on a change in the temperature such that the output wavelength is approximately the same as a desired wavelength. The assembly may further allow for perceived image distance adjustment using parallax mismatch.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation of U.S. patent applicationSer. No. 14/331,925, filed Jul. 15, 2014, which claims priority fromU.S. provisional patent application Ser. No. 61/879,393, filed Sep. 18,2013, U.S. provisional patent application Ser. No. 61/846,251, filedJul. 15, 2013, U.S. provisional patent application Ser. No. 61/883,532,filed Sep. 27, 2013, and U.S. provisional patent application Ser. No.62/005,262, filed May 30, 2014. The contents of each of which areincorporated herein in their entirety.

FIELD OF THE INVENTION

The present disclosure relates to a holographic image apparatus for usewith a weapon.

BACKGROUND OF THE INVENTION

Holographic gun sights are well known, but typical designs are complexand may be bulky or have high energy usage. Adjusting a holographic gunsight for windage and elevation has also presented challenges.Adjustment is required to align the positioning of a reconstructedreticle and to compensate for various weapon types and targetingprocedures. Existing systems have drawbacks. Accordingly there exists aneed in the art for an alternative or improved design for holographicgun sights.

Laser diodes are used in a wide variety of applications that require anarrow spectral width. However, the wavelength of the light produced bythe laser diode varies depending on a number of factors, includingchange in the temperature of the laser diode. For example, some laserdiodes will exhibit a shift in output wavelength of approximately 0.30nm/° C. The change in the temperature of the laser diode may be due toenvironmental conditions or due to heating from operation of the diode.For some applications, this shift in wavelength is not a problem.However, for other applications, such as a holographic gun sight, thisshift in the output wavelength may cause the holographic gun sight to beinaccurate.

In a holographic gun sight, the hologram reconstructs an image of areticle which will appear in focus at a distance in the viewing field(Virtual Image Plane). The sight is typically designed so that thisimage will overlap the target. Holographic diffractive optics may bewavelength dependent and the thus may be very sensitive to a change inthe laser diode wavelength. As the output wavelength shifts, thediffraction angle from a holographic element may change, which mayresult in a movement of the projected holographic image resulting in aninaccurate reticle position relative to the target.

To correct for this change in the output wavelength some sights haveachromatic holographic elements which compensate for changes in theoutput wavelength. However, it remains desirable (simpler design, easiermanufacturing, more reliable, lower cost) to provide a source of laserlight in which the output wavelength is stable as the temperaturechanges within an operating range. Similar considerations apply to otherdevices utilizing laser light, such as a stable LED, RCLED . . . etc.

One approach to addressing this problem is to control the temperature ofthe laser diode, such as through a use of a thermoelectric device or TECcooler. Such control may be open or closed loop. An open loop controlmay be used, such as a temperature sensor attached to the laser diode.As the sensor temperature changes, the TEC cooler keeps the diode at onestable temperature. For a closed loop system, the wavelength output ofthe laser diode may be directly monitored by a device such as a grating.This information is then used to adjust the temperature of the laserdiode via the thermoelectric cooler, and bring the diode back to adesired wavelength. While thermal control of the laser diode iseffective in preventing a change in wavelength, thermoelectriccontrollers are large in comparison to the laser diode and may draw acurrent in excess of 0.5 amps. For either case, using a thermoelectriccooler increases the physical size of the laser source assembly andgreatly increases its energy requirements. For this reason,thermoelectric controllers in gun sights are impractical and undesirableat this time. For example, US Patent Application Publication No.2014/0064315 discloses another means for incorporating a thermoelectriccontroller in a gun sight.

An alternative type of semiconductor laser diode is known as a VCSEL, orvertical-cavity surface-emitting laser. A VCSEL has improved temperaturestability as compared to a standard laser diode. For example, a VCSELmay have a wavelength shift of approximately 0.05 nm/° C., which isapproximately a six-fold improvement over a standard laser diode. Whilethis is a large improvement over the standard laser diode, even thissmaller amount of wavelength shift may be enough to impair the accuracyof a device using the VCSEL.

Parallax mismatch is another undesired result of using holography fortarget shooting. Parallax mismatch results when the reconstructedreticle, also referred to as a perceived image, is displayed on anobject either closer or farther than the intended distance. This meansthat the reconstructed reticle will appear to move around as the viewingeye moves. If the reconstructed reticle is displayed on an object at thepredetermined distance from the hologram apparatus, then the imageshould not move. It is desired that the reconstructed reticle remainsstill as the viewing eye moves about a display hologram when thereconstructed reticle is displayed on objects at varying distances. Thiseffect would improve shooting accuracy and precision. Accordingly, thereis a need for a holographic weapon sight that compensates for parallaxmismatch.

A dual H.O.E. assembly can present several challenges. For example, ifthe H.O.E. alignment in use does not match near perfectly with how theH.O.E. was recorded, then it results in an undesired imaging.Accordingly, a need exists to provide weapon sights with improvedholographic imaging in a compact and convenient setting.

SUMMARY OF THE INVENTION

The present disclosure is generally related to a sight assembly formounting to a weapon. The sight assembly may have one or more of thefeatures discussed herein. Some examples include an optical path with acarrier for a holographic optical element (H.O.E.) wherein a diode(specifically a wavelength stable light source in the presentembodiment, however, other stabilities including mechanical, brightness. . . etc. could also be utilized) is used as a virtual imagereconstruction source (or real image). The optical path may utilizemirrors or lenses. The H.O.E., the diode and the mirror are in a fixedangular configuration with respect to one another, but may be adjustedeither together or individually in a horizontal or vertical direction,or rotationally. The housing includes a transparent panel allowing lightto transfer therethrough and allowing the mirror, diode, and an H.O.E.to be in light communication with one another. Some examples include anadjusting mechanism with at least one screw having a shaft. Someexamples include adjustment of only the diode (stable lightsource/VCSEL). Others may include adjustment of the entire carrier, orof the holographic optical element. The shaft may include at least twoportions wherein the two portions of the shaft of the screw havedifferent pitch directions and/or pitch dimensions allowing for a slight(or magnified) adjustment of the carrier to adjust the assembly. Theassembly may have a fixed angular arrangement of the carrier, mirror,diode and holographic optical element. Additional features are disclosedherein.

Another aspect of the present invention relates to a stable lightsource. The present invention uses the VCSEL as a light source which isdriven in such a way that its wavelength output will remain stable. Thewavelength of the VCSEL is controlled by controlling the current it isgiven. This may be done by adjusting the amplitude of the current drivesignal. A detailed description of this is given below.

Further, the present disclosure is generally related to an assembly andmethod of correcting a parallax mismatch when viewing a reconstructedreticle through a weapon sight. The assembly may allow for a virtualimage distance adjustment. Accordingly, the virtual image plane can beadjusted. In an example, the virtual image plane may be adjusted betweena distance range of 25 meters to 500 meters. Using an adjusting lensand/or an adjusting light source, the virtual image plane may beadjusted so that the viewer sees the reconstructed image at a targetdepth.

Yet another aspect of the present invention relates to a chassis forholding holographic elements. The present disclosure is generallyrelated to a frame and/or chassis assembly for holographic weapon sightsand a method of making the same. A hologram frame assembly includes ahologram support operable for mounting a display hologram. A holographicoptical element (H.O.E.) support is also provided that is operable formounting a H.O.E. The H.O.E. support is spaced apart from the hologramsupport. A connector is provided for bridging the hologram support tothe H.O.E. support. A reference beam support is included for mounting areference beam source positioned to allow illumination of the H.O.E. Theframe is constructed to align the display hologram and the H.O.E. inrelative positions with respect to each other and near identical totheir respective relative positions at the time of their recording. Inan example, the frame assembly is fabricated as a single integral unit.

A compact weapon sight includes a housing having a base configured formounting on a weapon, a holographic optical element (H.O.E.), the H.O.E.supported by the housing, a light source operable to emit a beam oflight at an output wavelength when energized, the light source incommunication with the H.O.E., a power source operable to energize thelight source, a sensor for sensing a parameter of the light source and acontrol communicating with the sensor, the control operable to control acurrent from the power source to the light source, the control operableto adjust the current such that the output wavelength is approximatelythe same as a desired wavelength. In one embodiment, the sensor is atemperature sensor for sensing a temperature of the light source. Thetemperature sensor may be a voltage sensor operable to measure thevoltage of the light source during an off-period of a duty cycle.

In another embodiment, the sensor is a wavelength sensor for sensing awavelength of the light source. The sensor may be selected from of groupof sensor systems including: a passive dispersion sensor system whereina beam angle changes a fixed amount based on laser wavelength and thesystem includes one or more detectors for detecting beam angle changes,an interference filter system operable to output an optical signal thatpeaks at a center wavelength and the system includes a sensor forsensing the optical signal, an active dispersion sensor system wherein abeam angle changes by an adjustable amount based on laser wavelength andthe system includes one or more detectors for detecting beam anglechanges, an interferometric sensor system operable to produce wavelengthdependent fringes in space or time and the system includes one or moredetectors for sensing the wavelength dependent fringes, a polarizationbased sensor system operable to produce an output signal that peaks at acenter wavelength or a semiconductor-based wave meter operable toanalyze signal levels from two or more stacked detectors with differentspectral responses. Further, the control may control the current inpulses such that the light source is energized for an on-period and isnot energized for an off-period of a duty cycle. The light source may bea vertical-cavity surface emitting laser (VCSEL) diode. In oneembodiment, H.O.E. is a first H.O.E., the sight further comprising amirror, grating or second H.O.E., the light source illuminating themirror, grating or second H.O.E. and being reflected or diffracted toilluminate the first H.O.E. The position of the mirror, grating orsecond H.O.E. may be adjustable. The beam of light may illuminate theH.O.E. Further, the beam of light may be a non-collimated diverging beamof light.

The housing may include a chamber having a transparent portion, thelight source being sealed within the chamber. The weapon sight mayfurther include a carrier disposed in the chamber and a tie rod at leastpartially disposed in the chamber, the carrier connected to the tie rodso as to be pivotable about an axis of the tie rod wherein the lightsource is disposed on the carrier.

The weapon sight may further include a frame supporting the H.O.E. wherethe frame is disposed outside the chamber and connected to a portion ofthe tie rod extending outside the chamber and may further be structuredto include the frame and the carrier both being rotationally fixed tothe tie rod such that the light source and H.O.E. rotate together aboutthe axis of the tie rod. The chamber may be filled with nitrogen in anyof the embodiments.

The weapon sight may further include a carrier where the light sourcebeing disposed on the carrier, a frame supporting the H.O.E., and a tierod supported by the housing for rotation about an axis of the tie rod,the carrier and the frame both being connected and rotationally fixed tothe tie rod so as to be pivotable about the axis of the tie rod suchthat the light source and H.O.E. rotate together relative to the housingabout the axis of the tie rod.

Optionally, the weapon sight may include an elevation adjustmentmechanism for adjusting the rotational position of the carrier and framerelative to the housing, the elevation adjustment mechanism comprising,a shaft supported by the housing and rotatable with respect to thehousing, a first portion of the shaft having a first thread pitch, thefirst portion of the shaft threaded to a first member, the first memberfixedly connected to the housing and a second portion of the shafthaving a second thread pitch, the second portion threaded to a movablesecond member, the second member being rotationally fixed with respectto the housing and longitudinally movable with respect to the shaft, thesecond member connected to the carrier wherein the first thread pitch isdifferent from the second thread pitch so as to provide for fineadjustment of the carrier as the shaft rotates.

The assembly may also include a windage adjustment mechanism operable tomove the H.O.E. side to side with respect to the housing having a shaftsupported by the housing and rotatable with respect to the housing, afirst portion of the shaft having a first thread pitch, the firstportion of the shaft threaded to a first member, the first memberfixedly connected to the housing and a second portion of the shafthaving a second thread pitch, the second portion threaded to a movablesecond member, the movable second member being rotationally fixed withrespect to the housing and longitudinally movable with respect to theshaft, the second member connected to the H.O.E frame wherein the firstthread pitch is different from the second thread pitch so as to providefor fine adjustment of the H.O.E. frame as the shaft rotates.

The weapon sight may further entail the beam of light from the lightsource may be a readout light beam having a readout light beamphasefront, the H.O.E. is a display hologram that reconstructs a reticlewhen illuminated by the readout light beam, the reconstructed reticlehaving a perceived distance and the sight further comprising anadjustable feature operable for adjusting the readout beam phasefrontbefore illumination of the display hologram, wherein adjustment of theadjustable feature varies the perceived distance of the reticle image.

A movable lens may be positioned to modify the phasefront of the readoutlight beam prior to illuminating the display hologram. A holographicoptical element (H.O.E.) may be disposed in a position to be illuminatedby the light source, the H.O.E. reconstructing an angled readout lightbeam when illuminated by the light source, the angled readout light beamilluminating the display hologram.

The light source or the H.O.E. may be horizontally and/or verticallyadjustable by means of a multi-thread pitch adjustment assembly.Further, the base of the housing may be integral with a weapon. Theweapon sight may further include an accelerometer connected to thehousing adapted to improve battery life of the sight assembly.

The present invention provided for a weapon sight having a light sourceoperable for generating a readout light beam having a readout light beamphasefront, a display hologram spaced apart from the light sourceadapted to be illuminated by the readout light beam, the displayhologram reconstructing a reticle when illuminated by the readout lightbeam, the reconstructed reticle having a perceived distance and anadjustable feature operable for adjusting the readout beam phasefrontbefore illumination of the display hologram, wherein adjustment of theadjustable feature varies the perceived distance of the reticle image.The weapon sight may further include a power source operable to energizethe light source, a sensor for sensing a parameter of the light sourceand a control communicating with the sensor, the control operable tocontrol a current from the power source to the light source, the controloperable to adjust the current such that the output wavelength isapproximately the same as a desired wavelength. The sensor may be atemperature sensor for sensing a temperature of the light source. Thetemperature sensor may be a voltage sensor operable to measure thevoltage of the light source during an off-period of a duty cycle. Thesensor may be a wavelength sensor for sensing a wavelength of the stablelight source.

A movable lens may be positioned to modify the phasefront of the readoutlight beam prior to illuminating the display hologram. The adjustablefeature may engage the movable lens and is operable to adjust theposition of the movable lens with respect to the light source. Theadjustable feature may be an adjustment mechanism operable to adjust aposition of the light source with respect to the display hologram. Theadjustable feature may be an adjustment mechanism having an adjustmentscrew.

The weapon sight may further include a holographic optical element(H.O.E.) disposed in a position to be illuminated by the light source,the H.O.E. reconstructing an angled readout light beam when illuminatedby the light source, the angled readout light beam illuminating thedisplay hologram. The H.O.E. and display hologram may be positioned in arelative image orientation selected from reflection/transmission,reflection/reflection, transmission/reflection, andtransmission/transmission. The H.O.E. and the display hologram may befixed on a hologram chassis formed to mount both elements in a fixedrelationship to each other. A base with an attachment for mounting to anupper surface of a hand held weapon may also be provided.

The display hologram may be fabricated from a photopolymer. The lightsource may be a laser light source operable for generating a laser lightbeam. The laser light source may be a vertical-cavity surface emittinglaser (VCSEL) diode. The adjustable feature may include a rotatingadjustment that modifies the perceived distance incrementally from 25meters to 500 meters. The adjustable feature may include a rotatingadjustment that modifies the perceived distance continuously from 25meters to 500 meters. The H.O.E. may extend at least partially outsideof a housing. The housing may include a transparent portion and/or afilter providing for communication between the H.O.E. and the lightsource. The beam of light may illuminate the H.O.E., the beam of lightbeing a non-collimated diverging beam of light.

A method of correcting for parallax and adjusting a perceived distanceof a reconstructed image is provided including the steps of providing anassembly of the above and adjusting the adjustable feature to correspondto the distance of a target object.

A sight assembly for mounting to a weapon is provided including ahousing, a chamber provided within the housing a light source disposedwithin the chamber of the housing, a holographic optical element(H.O.E.), the H.O.E. in communication with the light source andreconstructing a reticle viewable by a user when illuminated by thelight source, the H.O.E. and the light source arranged in a fixedangular configuration, and an adjustment assembly adapted to adjust theholographic optical element and/or the light source, the adjustmentassembly connected to the housing, the adjustment assembly adapted tofinely adjust vertical or horizontal positioning of the holographicoptical element and/or the light source relative to the housing. Thechamber of the housing may be sealed. The assembly may further include acarrier and a tie rod, the carrier supporting the light source andconnected to the tie rod, a portion of the tie rod being disposedoutside of the chamber. The carrier may be pivotable about an axis ofthe tie rod. The chamber is filled with nitrogen. The adjustmentassembly may be a multi-thread pitch adjustment assembly.

The H.O.E. may extend at least partially outside of the housing. Thehousing may include a transparent panel providing for communicationbetween the H.O.E. and the light source. A mirror may be incommunication with the H.O.E. and the light source. The mirror may besealed within the chamber. A H.O.E. carrier may be provided to hold theH.O.E.

The sight assembly may further include a control for controlling thecurrent to the light source and a temperature sensor for sensing atemperature of the light source, the temperature sensor providing aninput to the control where the control being operable to adjust acurrent to the light source such that an output wavelength isapproximately the same as a desired wavelength.

The assembly may further include a control for controlling the currentto the light source and a wavelength sensor for sensing a wavelength ofthe light source, the wavelength sensor providing an input to thecontrol where the control being operable to adjust the current to thelight source such that an output wavelength is approximately the same asa desired wavelength.

An adjustment assembly for adjusting a component of a weapon sightincludes a shaft mounted at least partially within a housing, the shaftrotatable with respect to the housing, a first portion of the shafthaving a first thread pitch, the first portion of the shaft threaded toa first member, the first member fixedly connected to the housing, and asecond portion of the shaft having a second thread pitch, the secondportion threaded to a movable second member, the second member beingrotationally fixed to the housing and longitudinally movable withrespect to the shaft, the second member connected to an adjustablecomponent of the weapon sight, the first thread pitch being differentfrom the second thread pitch so as to provide for fine adjustment of thecomponent of the weapon sight as the shaft rotates. The first member maybe a nut fixed to the housing. The second member may be a nut. Thecomponent may be a carrier having a light source fixedly mountedthereto. The stable light source may be mounted within the housing. Aholographic optical element (H.O.E.) is mounted at least partiallyoutside of the housing. The housing may include a transparent portionproviding for communication between a mirror, the light source and theholographic optical element.

A sight assembly for mounting to a weapon is provided including ahousing having a chamber therein, a light source in communication with aholographic optical element, the light source and the H.O.E. positionedin a fixed angular arrangement, the light source and the holographicoptical element in communication with each other to produce areconstructed reticle viewable by a user and an adjustment assembly, theadjustment assembly adapted to adjust the vertical and/or horizontalposition of the light source with respect to the housing withoutdisrupting the fixed angular arrangement of the light source withrespect to the H.O.E. The assembly may further include a control forcontrolling a current to the stable light source and a temperaturesensor for sensing a temperature of the light source, the temperaturesensor providing an input to the control wherein the control is operableto adjust the current to the light source such that the outputwavelength is approximately the same as a desired wavelength. Further,the assembly may include a control for controlling a current to thelight source and a wavelength sensor for sensing a wavelength of thelight source, the wavelength sensor providing an input to the controlwherein the control is operable to adjust the current to the lightsource such that the output wavelength is approximately the same as adesired wavelength. A housing may be provided having a chamber, theH.O.E. and the stable light source are mounted within the sealedchamber.

A carrier may be provided connected to a tie rod, portion of the tie rodpositioned outside of the chamber, the carrier is pivotable about anaxis of the tie rod. The chamber may be filled with nitrogen. The lightsource may be horizontally and/or vertically adjustable by means of anadjustment assembly. The adjustment assembly may be a multi-thread pitchadjustment assembly. The H.O.E. may extend at least partially outside ofthe housing. The housing may include a transparent portion providing forcommunication between the H.O.E., a mirror and the light source. Amirror may be in communication with the H.O.E. and the light source. AH.O.E. carrier may be provided to hold the H.O.E. The light source maybe a VCSEL. An accelerometer may be provided connected to the housingadapted to improve batter life of the sight assembly.

A sight assembly for mounting to a weapon includes a housing having achamber therein, a light source in communication with a H.O.E., thelight source and the H.O.E. positioned in a fixed angular arrangement,the light source and the H.O.E. in communication with each other toproduce a reconstructed reticle viewable by a user, a tie rod, theH.O.E. connected to the tie rod, and an adjustment assembly, theadjustment assembly adapted to adjust the vertical and/or horizontalposition of the H.O.E. with respect to the housing without disruptingthe fixed angular arrangement of the light source with respect to theholographic optical element. The assembly may further include a controlfor controlling a current to the light source and a temperature sensorfor sensing a temperature of the light source, the temperature sensorproviding an input to the control wherein the control is operable toadjust the current to the light source such that an output wavelength isapproximately the same as a desired wavelength. Alternatively, theassembly further may include a control for controlling a current to thelight source and a wavelength sensor for sensing a wavelength of thestable light source, the wavelength sensor providing an input to thecontrol wherein the control is operable to adjust the current to thelight source such that an output wavelength is approximately the same asa desired wavelength.

A housing may be provided having a chamber, the H.O.E. and the stablelight source are mounted within the sealed chamber. The carrier may bepivotable about an axis of the tie rod. The chamber may be filled withnitrogen. The light source may be horizontally and/or verticallyadjustable by means of an adjustment assembly. The adjustment assemblymay be a multi-thread pitch adjustment assembly. The H.O.E. may extendat least partially outside of the housing. The housing may include atransparent portion providing for communication between the H.O.E., amirror and the light source. A mirror may be provided in communicationwith the H.O.E. and the stable light source. A H.O.E. carrier may beprovided to hold the H.O.E. The light source may be a VCSEL. Anaccelerometer may be connected to the housing adapted to improve batterylife of the sight assembly.

A sight assembly for mounting to a weapon is provided including ahousing having a chamber therein, a carrier, the carrier sealed withinthe housing, a mirror and/or a light source, the mirror and/or the lightsource mounted to the carrier, a H.O.E. mounted to the housing, thelight source in communication with the H.O.E. to produce a reconstructedreticle, the light source and the H.O.E. being in a fixed angulararrangement, and an adjustment mechanism operable to adjust the verticaland/or horizontal position of the light source or the H.O.E. withrespect to the housing without disrupting the fixed angular arrangementof the light source and the holographic optical element.

The assembly may further include a control for controlling a current tothe light source and a temperature sensor for sensing a temperature ofthe light source, the temperature sensor providing an input to thecontrol wherein the control is operable to adjust the current to thelight source such that an output wavelength is approximately the same asa desired wavelength. Alternatively, the assembly may include a controlfor controlling a current to the light source and a wavelength sensorfor sensing a wavelength of the stable light source, the wavelengthsensor providing an input to the control wherein the control is operableto adjust the current to the light source such that an output wavelengthis approximately the same as a desired wavelength.

A housing is provided having a chamber, the H.O.E. and the light sourceare mounted within the sealed chamber. The carrier may be pivotableabout an axis of the tie rod. The chamber may be filled with nitrogen.The light source may be horizontally and/or vertically adjustable bymeans of an adjustment assembly. The adjustment assembly may be amulti-thread pitch adjustment assembly. The H.O.E. may extend at leastpartially outside of the housing. The housing may include a transparentportion providing for communication between the H.O.E., a mirror and thelight source. A mirror may be provided in communication with the H.O.E.and the stable light source. A H.O.E. carrier may be provided to holdthe H.O.E. The light source may be a VCSEL. An accelerometer may beconnected to the housing adapted to improve battery life of the sightassembly.

An assembly for mounting to a weapon is provided having a H.O.E. and astable light wherein the stable light illuminates the H.O.E. toreconstruct a holographic image viewable by a user. The H.O.E. and thestable light source may be mounted to a housing. The stable light sourcemay be sealed within the housing. A mirror may be in communication withboth the H.O.E. and the stable light source.

The stable light source and the mirror may be sealed within a housing. Atransparent portion may be provided in the housing allowing the stablelight source and the mirror to communicate with the holographic opticalelement. The H.O.E. may be adjustable. The stable light source may beadjustable. A lens may be provided between the mirror and the stablelight source.

The assembly may further include a control for controlling a current tothe light source and a temperature sensor for sensing a temperature ofthe light source, the temperature sensor providing an input to thecontrol wherein the control is operable to adjust the current to thelight source such that an output wavelength is approximately the same asa desired wavelength. Alternatively, the assembly may further include acontrol for controlling a current to the light source and a wavelengthsensor for sensing a wavelength of the stable light source, thewavelength sensor providing an input to the control wherein the controlis operable to adjust the current to the light source such that anoutput wavelength is approximately the same as a desired wavelength. Theassembly may further include a carrier that is pivotable about an axisof tie rod. The housing may be sealed and filled with nitrogen.

A hologram frame assembly for use with a weapon sight includes ahologram support operable for mounting a display hologram, a H.O.E.support operable for mounting a H.O.E., the H.O.E. support spaced apartfrom the hologram support, a connector bridging the hologram support tothe H.O.E. support, and a reference beam support for mounting areference beam source positioned to allow illumination of the H.O.E.wherein the frame is constructed to align the display hologram and theH.O.E. in relative positions with respect to each other near identicalto their respective relative positions at the time of their recording.The reference beam support may extend from the hologram support to allowfor illuminating the H.O.E. in a reflective image generatingarrangement.

The reference beam support, the hologram support, the H.O.E. support,and the connector may be formed as an integral construction. The displayhologram and the H.O.E. may be in a parallel relationship with respectto each other. The hologram support defines a window sized and shaped tomount a display hologram. The H.O.E. support defines a window that issized and shaped to mount a H.O.E. The reference beam support defines anopening for mounting the reference beam source. The display hologram andthe H.O.E. each define a face having a surface area and wherein thesurface area of the face of the H.O.E. is less than the surface area ofthe face of the display hologram. The reference beam source may bealigned with the H.O.E. and the H.O.E. is positioned in an angledrelationship with respect to the display hologram. The H.O.E. mayreconstruct an angled beam pattern forming a readout beam forilluminating the display hologram. The connector may extend in an angledconfiguration having a pair of spaced apart support walls extending fromopposed edges of the hologram support to opposed edges of the H.O.E.support. A base connector may be provided for mounting to a hand gun orweapon.

A method of making a holographic weapon sight is provided including thesteps of providing a hologram frame assembly having a hologram support,a H.O.E. support, a reference beam support, and a connector bridging thehologram support to the H.O.E. support; forming a display hologrammounted within the hologram support by illuminating a recordable mediumwith a readout beam and an object beam; recording a H.O.E. mountedwithin the H.O.E. support spaced apart from the hologram support byilluminating a recordable medium with a readout beam and a referencebeam such that when recorded and illuminated by the reference beam, thereadout beam is recreated; and mounting a reference beam source withinthe reference beam support positioned to allow illumination of theH.O.E. wherein the frame is constructed to align the display hologramand the H.O.E. in relative positions with respect to each other nearidentical to their respective relative positions at the time of theirrecording.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1a discloses an exploded perspective view of the sight assembly;

FIG. 1b illustrates an assembled perspective view of the sight assembly;

FIG. 2 illustrates a perspective view of the holographic opticalelement, holographic optical element carrier, and the carrier allconnected to the tie rod;

FIG. 3a illustrates an assembled perspective view of the holographicoptical element, holographic optical element carrier, and the carrierall connected to the tie rod also having the windage adjustment screwattached thereto;

FIG. 3b illustrates a cross-sectional view of the adjustment screwassembly;

FIG. 3c illustrates a cross-sectional view of an alternative embodimentof the screw assembly operable to move the light source;

FIG. 4 illustrates an exploded perspective view of the holographicoptical element, holographic optical element carrier and the carrier allconnected to the tie rod also having the windage adjustment screwattached thereto;

FIG. 5 illustrates an assembled perspective view of the elevationadjustment screw;

FIG. 6 illustrates an exploded side view of the elevation adjustmentscrew;

FIG. 7 illustrates a cross sectional view of the assembly of the sight;

FIG. 8 illustrates an example hologram image assembly according to thepresent disclosure in a reflection/transmission configuration;

FIG. 9 illustrates an example hologram image assembly according to thepresent disclosure in a reflection/reflection configuration;

FIG. 10 illustrates an example hologram image assembly according to thepresent disclosure in a transmission/transmission configuration;

FIG. 11 illustrates an example hologram image assembly according to thepresent disclosure in a transmission/reflection configuration;

FIG. 12 illustrates an example of wavefront/phasefront propagation;

FIG. 13 illustrates an exemplary holographic testing system;

FIG. 14 illustrates a schematic configuration of the H.O.E., mirror andstable light source;

FIG. 15 illustrates a schematic configuration of the H.O.E., mirror andmovable stable light source;

FIG. 16 illustrates a schematic configuration of the H.O.E. and fixedstable light source;

FIG. 17 illustrates a schematic configuration of the H.O.E. and movablestable light source;

FIG. 18 illustrates a schematic configuration of the H.O.E., mirror andstable light source having an optional lens between the stable lightsource and the mirror;

FIG. 19 illustrates a schematic configuration of the H.O.E., stablelight source and hologram without a mirror; and

FIG. 20 illustrates a perspective view of the chassis and hologramholder of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates generally to a sight assembly for a weaponfor reconstructing a virtual image used to assist in operation of theweapon. Particular examples will be described, including a variety offeatures. It should be understood that other examples may include one ormore of these features in any combination.

The illustrated assembly incorporates a wavelength tunable light source(specifically a VCSEL). The assembly allows for slight adjustment of thefixed assembly and a sealed configuration to achieve an improved sightassembly.

Gun Sight Assembly and Adjustment

FIG. 1a illustrates an exemplary holographic gun sight assembly 10having a housing 12. The housing 12 has an interior chamber 11 definedtherein. As shown, the interior chamber 11 extends downwardly from anupper surface of the housing 12. A clear window, not shown, covers theopening in the upper surface. The elements contained within the chamber11 in the housing are sealed therein to prevent dust or moisture fromentering the housing. The chamber may also be filled with Nitrogen, thusrequiring a secure seal.

The gun sight of the present invention is compact and intended for usewith a hand held weapon. Compact being defined as occupying little spacecompared with others of its type. Accordingly, the gun sight of thepresent invention is significantly smaller and occupies less space ascompared to similar gun sights. Furthermore, “hand held” is defined asbeing for use with a refile, handgun, pistol . . . etc. or any otherknown weapon commonly used in a hand held manner. “Hand held” way alsoinclude weapons mounted to a tripod (or other mount) but small in nature(small compared to a vehicle or airplane). Hand held includes all othernon-vehicle (i.e. a tank) weapons.

A holographic subassembly is mounted to the housing such that portionsof the subassembly are within the chamber 11 and portions are outsidethe chamber. The subassembly is shown at 8 in FIG. 2. The subassembly 8includes an elongated carrier 13 that has a forward end 17 connected toa tie rod 24. The carrier 13 supports a laser diode 15 (or other stablelight source), which is preferably a VCSEL, and a mirror 14. A H.O.E.carrier or frame 18 (or 22) supports a H.O.E. 16 generally perpendicular(or at a slight angle) to the carrier 13. The H.O.E. frame 18 includesan attachment portion 20 at its lower end. The attachment portionengages the tie rod 24 allowing the H.O.E. frame to connect at the sameconnection point as the carrier 13. The H.O.E. frame and the carrier arepreferably both rotationally fixed to the tie rod such that the angularpositions of the diode 15, mirror 14 and H.O.E. 16 are fixed. The diode15 produces light that is reflected off of the mirror 14 into the H.O.E.16. The H.O.E. refers to an element having a recorded image or effectthereon operable to manipulate a wave pattern or beam when illuminated.An H.O.E., for example, can recreate a readout beam in combination withbeam expansion.

Unlike many prior art holographic image assemblies, the diode 15, mirror14 and H.O.E. 16 are not part of an achromatic system of opticalcomponents.

The components forming the subassembly 8 of FIG. 2 are also shown inFIG. 1a , in an exploded view. The cross-sectional side views of FIG. 7help to illustrate the relationship between the subassembly 8 and thehousing 12. The carrier 13, with the diode 15 and mirror 14, aredisposed in the chamber 11. A transparent window 21 covers the chamber11 such that the diode 15 and mirror are sealed into the chamber andprotected from dust and humidity. A first portion 25 of the tie rod 24engages the carrier 13 and is inside the chamber 11. However, a secondportion 27 of the tie rod 24 extends through the housing 12 to aposition outside this chamber 11. In the illustrated embodiment, thefirst portion 25 is a first end of the tie rod and has a non-circularshaped cross-section, as shown. The forward end 17 of the carrier 13 hasa corresponding non-circular shaped cross-section for receiving thefirst end 23 of the tie rod 24. Because the first end 23 and the openingin the forward end 17 of the carrier have corresponding non-circularshapes, they are rotationally fixed to one another while also allowingthe tie rod 24 to move along its axis with respect to the carrier 13. Inthe illustrated embodiment, the second portion 27 of the tie rod isfluted so as to tightly engage the opening in the attachment portion 20of the H.O.E frame 18. The tie rod 24 and H.O.E. frame 18 are thereforerigidly attached to one another. The H.O.E. frame 18 and H.O.E. 16 areoutside the chamber 11 but the tie rod rotationally ties the H.O.E.frame 18 and carrier 13 together such that their relative rotationalpositions remain the same despite part of the subassembly 8 being in thechamber and part being outside the chamber.

The tie rod 24 allows for a seal to be created to thus seal out anymoisture or dust which can enter the housing and interfere withproduction of the hologram. The seal may be created by a tight fitbetween the tie rod and the housing and the tie rod and the carrier, byseals, or by flexible rubber or plastic, or like materials.

The housing 12 further includes apertures 26 a, 26 b where the batteriesare stored for operation of the sight. The housing 12 further includes acap 28 secured to the housing by means of a screw 30. The screw includesa head 72. The cap 28 encloses the batteries held within the apertures26 a, 26 b. The cap 28 is removably attached allowing a user to replacethe batteries.

The position of the carrier 13 and H.O.E. frame 18 are adjusted by meansof windage and elevation adjustors, which may use a multi-pitch screw.In a preferred embodiment, the screw or bolt of each adjustor includestwo portions wherein each portion has a different thread pitch and/ordifferent thread direction thus allowing for very fine adjustment. Twonuts are provided where one is fixed and the other is movable. Theconfiguration of the dual nut assembly and relationship to the carrieris clearly illustrated in FIG. 7. FIG. 1a shows the same components inan exploded view. FIG. 5 shows an assembled elevation adjustmentassembly and FIG. 6 shows an exploded view. A first nut 41 is fixed tothe housing. A shaft 43 rotates relative to the fixed first nut 41,thereby moving up and down (or sideways if adjusting windage). Becauseof the varied threads on either the second nut 58 or on the shaft 43,when the shaft is rotated, the nut moves faster (or slower) as comparedto the shaft because of the varied thread, A second nut engages thecarrier 13 and is prevented from rotating relative to the housing andcarrier. Therefore, the shaft 43 rotates relative to both the fixed nut41 and the second nut. If the two nuts were to have the same directionand pitch of threads, the spacing between the nuts would remainconstant. By changing the pitch or the thread of the two nuts, thespacing between the nuts will change as the shaft rotates.

The adjustment provides a fixed elevation adjustment wherein it movesthe subassembly 8, by rotating the subassembly about the pivot axisdefined by the tie rod. Therefore, the diode, the H.O.E., and the mirrormove relative to the housing 12. The elevation adjustment assembly 40includes the shaft 43 having a first portion 42 and a second portion 44.The shaft is connected to a threaded hole 46 (or nut) which is connectedto the housing 12. The nut 46 (or housing portion) is fixed. The movablethreaded nut 50 is provided with a pitch different than the nutconnected to the housing. These two nuts may have a right-hand thread ora left-hand thread, but preferably each have the same direction ofpitch. Alternatively, they may have opposite pitch, but this magnifiesthe adjustment. Preferably the first portion 42 has a coarser pitch thanthe second portion, as shown in FIG. 6. This allows for very fineadjustment of the carrier position. A floating bolt head 52 engages thetop of the shaft 43, allowing the user to rotate the shaft and thusadjust the elevation of the carrier. Adjustment may be made by ascrewdriver, lever, handle, etc. allowing the user to rotate theshaft/bolt.

This same fine adjustment movement is also illustrated in the windageadjustment assembly 60, as shown in FIGS. 1a, 3a-3c and 4. The windageadjustment assembly 60 includes a shaft having a first portion 62 and asecond portion 64. A first and second nut are both provided wherein afirst nut is connected to, or forms part of, the housing and a secondnut 68 is provided which moves side to side. The moving nut includes anend portion which abuts and engages the carrier 13 and when the shaft isrotated moves the carrier to adjust the windage. As discussed above, thetie rod 24 may move linearly in the opening in the carrier 13. As thewindage adjustment presses on the tie rod, the tie rod 24 and frame 18,which is fixed to the carrier 13, moves side to side. Spring preloadsthe tie rod against the windage adjustment. Nut 68 is the stationarynut, captured in the housing 12. The tie rod 24 would serve as themoveable (sliding) nut. This allows the frame 18 and tie rod 24 to slideis unison while the profile of the first portion 25 of the tie rod and17 of the carrier keep the frame 18 in a fixed angular position.

FIG. 3c illustrates a cross-sectional view of an alternative embodimentof the screw assembly operable to move the light source including astationary nut 69, a movable nut 71 and a support pin 73. Nut 69 is thestationary nut, captured in the housing. This allows the frame (orcarrier) to slide in unison keeping the H.O.E., light source and mirrorin a fixed angular position.

This fine movement of the adjustment screws discussed above allows formovement of the perceived image in a very minimal way. Due to the natureof the hologram, little if any distortion is perceived from thismovement. Set screws with nylon tips could eliminate any movement due totolerance.

Various configurations of the H.O.E., mirror, light source, lens andcorresponding adjustment mechanisms can be utilized. By way of example,FIGS. 14-18 illustrate just a few of the arrangements of the H.O.E.,mirror, light source, lens and corresponding adjustment mechanisms. Anyof the following arrangements described below and illustrated in FIGS.14-18 may be utilized in the housing and with the adjustment mechanismsdescribed in this specification. Further, any of the followingarrangements described below and illustrated in FIGS. 14-18 may besealed within a housing or utilize the parallax mismatch or VCSELtechnology discussed below.

Now referring to FIG. 14, a fixed light source 116 is in directcommunication with a mirror 119. The mirror is accordingly in directcommunication with the movable image or H.O.E. 113. In one embodiment,the mirror 119 and the light source 116 are sealed within a housing. TheH.O.E. 113 may be provided outside of the housing and able tocommunicate with the mirror through a transparent panel in the housing.The viewer 111 is then able to view the image on the H.O.E. 113. TheH.O.E. 113 may be movable side to side, up and down and/or may pivot orrotate about a horizontal or vertical axis to achieve windage andelevation adjustment and/or fine tuning the position of the perceivedimage. This movement may be achieved with any type of adjustingmechanism. In this embodiment, the position of the source 116 and mirrorare both fixed.

Now referring to FIG. 15, a movable light source 116 is in directcommunication with a mirror 119. The mirror is accordingly in directcommunication with the image or H.O.E. 113. The H.O.E. 113 is fixed inthis configuration. In one embodiment, the mirror 119 and the movablelight source 116 are sealed within a housing. The H.O.E. 113 may beprovided outside of the housing and able to communicate with the mirrorthrough a transparent panel in the housing. The viewer 111 is then ableto view the image on the H.O.E. 113. The movable light source 116 ismovable by means or a track, an adjustment screw (such as discussedabove) or any other suitable means for recreating movement. The source116 may be movable side to side, up and down and/or may pivot or rotateabout a horizontal or vertical axis to adjust aspects of the perceivedimage.

Now referring to FIG. 16, a simplified arrangement is disclosed,eliminating the need for a mirror. FIG. 16 illustrates a fixed lightsource 116 in direct communication with a movable image or H.O.E. 113.The H.O.E. 113 is movable in this configuration. In one embodiment, thelight source 116 is sealed within a housing. The H.O.E. 113 may beprovided outside of the housing and able to communicate with the mirrorthrough a transparent panel in the housing. In other embodiments, theH.O.E. 113 and the light source 116 are all sealed within the housing.The viewer 111 is then able to view the image on the H.O.E. 113. Themovable H.O.E. 113 is movable by means or a track, an adjustment screw(such as discussed above) or any other suitable means for recreatingmovement. The H.O.E. 113 may be movable side to side, up and down and/ormay pivot or rotate about a horizontal or vertical axis to achievewindage and elevation adjustment and/or fine tuning the position of theperceived image.

Now referring to FIG. 17, another simplified arrangement is illustrated,also eliminating the need for a mirror. FIG. 17 illustrates a movablelight source 116 in direct communication with a fixed image or H.O.E.113. Light source 116 is movable in this configuration. In oneembodiment, the movable light source 116 is sealed within a housing. TheH.O.E. 113 may be provided outside of the housing and able tocommunicate with the mirror through a transparent panel in the housing.In other embodiments, the H.O.E. 113 and the light source 116 are allsealed within the housing. The viewer 111 is then able to view the imageon the H.O.E. 113. The movable light source 116 is movable by means or atrack, an adjustment screw (such as discussed above) or any othersuitable means for recreating movement. The source 116 may be movableside to side, up and down and/or may pivot or rotate about a horizontalor vertical axis to adjust aspects of the perceived image.

Now referring to FIG. 18, an optional version arrangement is shown,including an optional lens 115. The lens 115 can be used to change thephasefront or wavefront of the emitting light before illuminating theH.O.E. 113 or the mirror 114. The light source 116 is provided incommunication with the mirror 114 through the optional lens 115. Eitherthe mirror 119 or the light source 116 may either be fixed or movable.The mirror 119 is then in communication with the H.O.E. 113. In oneembodiment, the mirror 114, the lens 115 and the light source 116 areall sealed within the housing. The H.O.E. 113 may also be sealed withinthe housing. The viewer 111 is then able to view the image on the H.O.E.113.

Additional embodiments may include any combination of the arrangementsin FIGS. 14-18. For example, both the light source and H.O.E may bemoveable and a lens may be provided. The lens may also be repositioned,such as being between the mirror and image, or more than one lens may beused. The mirror in any embodiment may be replaced with an H.O.E. thatrecreates a beam for illuminating the image H.O.E.

Parallax Mismatch

Referring now to FIGS. 8-12, the present disclosure may incorporate anassembly 110 for holding one or more H.O.E.s and for use with a weaponsight. The various assemblies disclosed in FIGS. 8-12 may be used withthe assembly as discussed above and in the attached claims. The assembly110 allows for adjustment of a perceived distance of a reconstructedreticle 118. A reconstructed reticle is defined as a virtual imagecreated by the H.O.E.

The assembly 110 includes a display hologram 112, also referred to as ahologram 112. The configurations as illustrated in FIGS. 8-12 may beincorporated within the housing of the present invention (or at leastpartially sealed within the housing). FIGS. 8, 9, 10 and 11 demonstratepaths configured to utilize two H.O.E. components. This configurationand technique may provide reduced wavelength effects. The first H.O.E.shapes the beam (not possible with grating) hence creating an opticalconfiguration not previous geometrically possible with grating and anH.O.E.

Display hologram 112 includes a holographic wavefront of a reticle 119(also referred to as wavefront 119) recorded thereon using any knownrecording technique. Wavefront 119 onto hologram 112 can includeemitting a reference beam and an object beam in the presence of areconstructed reticle or image mask thereby recording the image onto thedisplay hologram. In one example, hologram 112 can be fabricated from afilm material requiring chemical development. In this example, hologram112 is fabricated from a photopolymer which eliminates the need forcostly and hazardous chemical processing.

Wavefront 119 recorded on hologram 112 allows for a reconstructedreticle 118 to be displayed at a perceived distance from the assembly110. The image is viewed by a user represented schematically as viewingeye 111. Displaying a perceived image 118 occurs when hologram 112 isilluminated by a readout beam corresponding to or matching the lightbeam used during recording. In one example, the hologram is illuminateddirectly from a reference light beam source. In this example, thereadout light beam is an angled light beam 120 from an H.O.E. 113.Angled light beam 120 is a readout beam in these examples. In anotherexample, a grating can be used.

H.O.E. 113 can also be fabricated from a photopolymer. In this example,diffracted light from H.O.E. 113 (light beam 120) illuminates the H.O.E.112. Accordingly, light source 116, when activated, emits a light beamthat illuminates H.O.E. 113. In an example, light source 116 can be alaser light source operable for emitting a laser light beam. In afurther example, the laser light source is a vertical-cavitysurface-emitting laser (“VSCEL”). Any other narrow spectrum source mayalso be utilized.

A lens 115 can be provided between the light source 116 and the H.O.E.113. Lens 115 can be used to change the phasefront or wavefront of thelight before illuminating. FIG. 12 illustrates how the wavefront oflight waves propagate (and become flatter with distance) as they moveaway from the source. Adjustment of the phasefront corrects for parallaxmismatch of the perceived image 118 by adjusting the perceived distanceof the perceived image. The phasefront can be adjusted by adjustingeither the lens 115 position or the light source 116 position, relativeto the H.O.E. 113. In this example, the lens 115 can be adjusted along alens adjustment track 114. Lens adjustment track 114 can be adjustedmanually by hand either continuously or incrementally corresponding tovarying perceived distances. Likewise, light source 116 can be adjustedvia a light source adjustment track 117. In an example, more than onelens is used and it is conceivable that lens assemblies having aplurality of lenses are used. It is further possible that these lensescan be individually or collectively adjusted to generate variousmagnifications. In yet a further example, adjustment of the position ofthe H.O.E. and/or the display hologram can also impact the perceiveddistance of the reconstructed reticle.

The present disclosure further provides for a base with an attachmentfor mounting to an upper surface or rail of a weapon. The base couldalso be the weapon itself. The assembly is also operable to mountdirectly to the weapon without the need of a separate base. Theadjustable feature can include a rotating adjustment that modifies thereconstructed reticle perceived distance incrementally from 25 meters to500 meters. In a further example, the adjustment occurs incrementally bya factor of 25 meters. In an alternative embodiment, the adjustablefeature includes a rotating adjustment that modifies the target imageperceived distance continuously from 25 meters to 500. The adjustablefeature corrects for parallax by adjusting the reconstructed reticledistance to align with the actual distance of a reconstructed reticle.The perceived image is displayed on the target image and if positionedat the right distance, the image will not move with slight movements ofthe viewing eye (i.e. no parallax).

VCSEL

A gun sight in accordance with the present invention may alsoincorporate the thermal control referred to herein as smart lightcontrol. Thermal stability of the virtual image, or the observedposition of the reconstructed reticle, is achieved by using a wavelengthtunable source which may be a VCSEL. The need for stability is aconsequence of the changes in ambient temperature. A VCSEL as a lightsource is used which is driven in such a way that its wavelength outputwill remain stable. The wavelength of the VCSEL is controlled bycontrolling the current it is given. The smart light control varies theamplitude of the laser current to correct for wavelength drift caused bytemperature changes. Alternatively, the control system may be used toadjust the wavelength to a desired wavelength.

In some examples, a pulse width signal is used to energize the VCSEL. Assuch, the VCSEL is energized and on for an on-period and turns off foran off-period. This on/off cycling is very rapid such that the laserlight produced by the VCSEL may appear as substantially constant to ahuman observer. Brightness is adjusted by varying the duty cycle. Theduty cycle can be changed by (1) modulating the pulse width and/or (2)varying the pulse repetition frequency (PRF).

In some versions, an open loop control system is used to control theVCSEL. In this example, the temperature of the VCSEL is monitored andthen the current to the VCSEL is adjusted to a value based on the knownor tested characteristics of the VCSEL. In some examples, thetemperature of the VCSEL is determined by measuring the temperatureusing a thermocouple or other temperature sensing element in closeproximity to the VCSEL. Any approach to temperature sensing may be used.In another approach, the VCSEL is “interrogated” with a low level biascurrent during the off-period of the duty cycle. As known to those ofskill in the art, the voltage of the VCSEL will change with temperature.This allows the temperature of the VCSEL to be directly determined. Thisinformation is then used by the control system to adjust the currentinput during the subsequent on-periods of the cycle. Alternatively, thecontrol may be a temperature control from another area, such as near theVCSEL.

In an alternative approach, a closed loop control system is used whereina wavelength sensor measures the output wavelength of the VCSEL. Thisinformation may then be used by the control system to adjust the currentto the VCSEL, allowing a desired output wavelength to be achieved.Example sensor systems are:

-   -   a) Passive dispersion (e.g. grating or prism) changes the beam        angle a fixed amount based on laser wavelength with the sensor        being one or more detectors.    -   b) Interference filter (e.g. Bragg notch filter, Fabry-Perot)        outputs an optical signal that peaks at a center wavelength and        is sensed by one detector.    -   c) Active dispersion (e.g. AOM and AOTF) changes the beam angle        an adjustable amount based on laser wavelength with the sensor        being one or more detectors.    -   d) Interferometric (e.g. FTIR and Sagnac) produces wavelength        dependent fringes in space or time and is sensed by one or more        detectors.    -   e) Polarization (e.g. polarizer and analyzer) produces an output        signal that peaks at a center wavelength.    -   (f) Semiconductor-base wave meters analyze signal levels from        two or more stacked detectors with different spectral responses.

Case (a) can also be implemented by integrating the wavelength gratinginto the hologram. For example, when the hologram was constructed asecond object beam would be introduced, that when readout wouldilluminate the one or more detectors.

Cases (a) and (b) when a single detector is used, the controller willneed to dither the laser wavelength to maintain the maximum signal. Thedithering will also shift the reticle and must be limited to a narrowrange; this effect can be avoided at the cost of two or more sensors.For cases (a) and (b) two or more sensors will produce two signals thatcan be adjusted to some desired levels and avoids dithering.

Case (c) uses dithering that is applied to a piezoelectric and producesa beam steering similar to case (a). This dither, however, doesn'taffect the reticle position and can be sensed by any detectorconfiguration.

Cases (d), (e), (f) would be operated in the conventional wavelengthsensing modes.

The control system may use one or multiple inputs, such as informationfrom a wavelength sensor, a temperature sensor, or other information.

In accordance with a further aspect of the present invention, aholographic sight is constructed including a VCSEL and a current controlsystem as described above. Alternatively, any other wavelength stablelight source may be used. Such a sight may reduce or eliminate the needfor an achromatic system and may achieve higher levels of wavelengthstability over an operating temperature range. In one example, thewavelength output of a VCSEL may change by approximately 2 nanometersover a 40° Celsius temperature range. The same VCSEL may have a currentsensitivity such that a change in current will cause a 2 nanometerchange in the wavelength, thereby allowing complete compensation forwavelength shift. Such a holographic sight may include an open loop or aclosed loop control system as described above. In a further example, thecontrol system may be used to adjust the position of a holographic imagein the sight. For example, changes in wavelength may cause a change inthe perceived vertical position of the holographic image in the sight.As such, the wavelength may be adjusted so as to compensate forelevation. For example, the current level may be changed so as to raiseor lower the perceived position of the holographic image, depending onthe design of the sight. As such, the present invention allowselectronic adjustment of elevation in certain embodiments.

Referring now to FIG. 13, an exemplary holographic testing system isillustrated, utilizing a VCSEL with current control of wavelength inaccordance with certain embodiments of the present invention. The systemincludes a VCSEL 210 that emits a spreading beam of light 212. Awavelength sensor 214 may be disposed at least partially in this beam,for use as part of a closed loop control system. In the illustratedembodiment, a collimating lens 216 collimates the light 212 into acollimated beam 218, and this beam 218 illuminates the hologram 220. Inthis testing system, a camera 222 is focused on the reconstructed imageso as to monitor the position of the reconstructed image. The cameraimage is then viewable on a computer 224. A VCSEL current controlcircuit 226 controls the current, duty cycle, and other factors of thesignal provided to the VCSEL 210. The control circuit 26 may receiveinput from a wavelength sensor 214 and a temperature sensor 228, whichis located in close proximity to the VCSEL. Alternatively oradditionally, the voltage of the VCSEL may be measured during theoff-period of the duty cycle and used to determine the temperature ofthe VCSEL. A voltage measurement element is shown at 230. As will beclear to those of skill in the art, the illustrated system allows thewavelength output of the VCSEL to be controlled so as to achieve astable wavelength across a temperature operating range and/or to allowadjustment of the perceived image.

A VCSEL with a current control system as described above may also beused with a variety of other laser devices. For example, certain typesof imaging systems utilize a laser light source and it may be useful toadjust or control the output wavelength of the laser light source. Suchapplications form other embodiments of the present invention.

Extended battery life is achieved by using an accelerometer to bring theunit in and out of a low power mode. When the user is not moving thedevice (i.e. time delay), the unit automatically goes into a low poweror power saving mode. The diode will power down to a nonvisible opticalpower such as a standby mode. When the user moves the device theoriginal optical power is then returned. An accelerometer may also beused to provide other feedback to the user including, but not limitedto, using targeting stability and recoil intensity.

A photodiode is used to sense ambient levels for use with an embeddedcontroller to adjust brightness to the user's eye automatically. Theembedded controller remembers brightness levels. The embedded controlleris operable to remember the previous setting. The system also includeson-off options for the energy saving and the photodiode. These on-offswitches may be provided on the cap 28 of the housing 12.

The assembly further includes a transparent portion or a filter mountedto a top portion of the housing 12. The transparent panel allows thediode and mirror to remain sealed within the housing but provides forthe hologram outside of the housing to conserve space. The transparentpanel attached to the housing allows the diode and the mirror to be incommunication with the hologram 16 allowing light to pass through thetransparent portion of the housing. This holographic sight includes theillumination source and the H.O.E. The H.O.E. reconstructs the virtualimage of the reticle at a known distance to produce a reconstructedreticle.

H.O.E. Frame and Chassis

Another embodiment is generally related to a frame and/or chassisassembly for holographic weapon sights and a method of making the same.A hologram frame assembly includes a hologram support operable formounting a display hologram. A holographic optical element (H.O.E.)support is also provided that is operable for mounting a H.O.E. TheH.O.E. support is spaced apart from the hologram support. A connector isprovided for bridging the hologram support to the H.O.E. support. Areference beam support is included for mounting a reference beam sourcepositioned to allow illumination of the H.O.E. The frame is constructedto align the display hologram and the H.O.E. in relative positions withrespect to each other identical to their respective relative positionsat the time of their recording. In an example, the frame assembly isfabricated as a single integral unit.

Referring to FIGS. 19 and 20, the present disclosure provides for aholographic image frame and/or chassis assembly 300 for use with aweapon sight. Assembly 300 is a frame or chassis assembly having ahologram support 311 spaced apart from a H.O.E. support 313. Hologramsupport 311 and H.O.E. support 313 are physically bridged by a connector312. Connector 312 maintains the desired spacing of the hologram support311 from H.O.E. support 313 and maintains the supports in a fixedrelationship with respect to each other. In an example, chassis assembly300 is fabricated as a single integral unit.

In this example, hologram support 311 and H.O.E. support 313 each definea window (316, 317) for mounting and receiving a corresponding imagemedium (321, 323) respectively. The hologram support 311 defines ahologram window 316 sized and shaped to mount and receive a displayhologram 321. In this example, the display hologram 321 and the hologramwindow 316 define a relatively rectangular or square geometry. Similarto the hologram support 311, the H.O.E. support 313 defines a H.O.E.window 317 sized and shaped to mount and receive a H.O.E. 323. In thisexample, the display hologram 321 and thus the hologram support 311 isrelatively larger than H.O.E. 323 and H.O.E. 313. Accordingly, each ofdisplay hologram 321 and H.O.E. 323 can define a face having a surfacearea wherein the surface area of the display hologram 321 is larger thanthe surface area of the H.O.E. 323.

Chassis 300 further includes a reference beam support 314 sized andshaped to mount and receive a reference beam source 324. In thisexample, the reference beam support 314 extends from and is integrallyformed with hologram support 311. In an example, the reference beamsupport 314 can extend downward from hologram support 311 placingreference beam 325 directly below display hologram 321 when chassis 300is in an upright position or mounted on a weapon. Reference beam source324 is operable for forming a light beam or reference beam 325. In anexample, the reference beam is a laser and in a further example, thereference beam source 324 is a vertical-cavity surface-emitting laser(“VSCEL”). When activated, reference beam source 324 should bepositioned to illuminate H.O.E. 323 with the reference beam 325. In anexample, chassis 300 is sized and shaped to mount on a hand gun.

Chassis 300 is operable for mounting and receiving a display hologram321 (also referred to as a hologram 321) and a H.O.E. 323. An H.O.E.refers to an element or object having an image or effect recordedthereon operable to manipulate a wave pattern or beam when illuminated.An H.O.E., for example, can recreate a readout beam in combination withbeam expansion. This can allow for having a relatively smaller sizedH.O.E. as compared to a display hologram.

In the example of FIGS. 19 and 20, reference beam 325, when activated,illuminates H.O.E. 323 which forms a readout beam 315 to illuminatedisplay hologram 321. When illuminated by the readout beam 315, displayhologram 21 displays a reticle image visible at a distance in a viewingfield. The reticle image is recorded on the display hologram 321. Thereadout beam is recorded on the H.O.E. 323. In an example according tothe present disclosure, the display hologram 321 and the H.O.E. 323 arerecorded in a fixed relationship with respect to each other through theuse of the chassis 300.

The recording of display hologram 321 and H.O.E. 323 occurs according toa method of the present disclosure. For recording the elements 321 and323, reflective imaging is used for recording of the H.O.E. 323 andtransmission imaging is used for recording of the display hologram 321.However, it is within the scope of the present disclosure to usereflective/reflective, transmission/reflective, andtransmission/transmission imaging configurations.

For recording of the display hologram 321, a recordable medium ismounted and fixed in position of the hologram support window 316. Therecordable medium can be any element operable for recording of ahologram image or reticle. In an example, the recordable medium isself-developing photopolymer. Recording a reticle image onto displayhologram 321 can include emitting a readout beam and an object beam inthe presence of a target image or image mask thereby recording the imageonto the display hologram. In one example, hologram 321 can befabricated from a film material requiring chemical development. In thisexample, hologram 321 is fabricated from a photopolymer which allows theimage to self-develop, thus eliminating the need for costly andhazardous chemical processing.

Once the photopolymer is fixed into position within the hologram supportwindow 16, a readout beam source 350 and a reticle beam source or objectbeam source (not shown) are positioned into desired alignment. Thereadout beam source 350 generates a readout beam 315 which records thelight and thus the image formed by the object beam source. Often, theobject beam source engages an image mask which records a desired imageon the recordable medium. For example, cross hairs, a circle, or asingle dot can be used as a reticle. Typically, the H.O.E. 323 isrecorded following recording of the display hologram 321. However, thepresent disclosure is not limited to this order of operation.

For recording the H.O.E. 323, a recordable medium such as a photopolymeris mounted and fixed in position of the H.O.E. support window 317. Thephotopolymer is then exposed to both the readout beam 315 from thereadout beam source 350 and the reference beam 325 from the referencebeam source 324. This records the readout beam 315 on H.O.E. 323.Accordingly, when chassis 300 is in use and reference beam source 324 isactivated, H.O.E. 323 is illuminated by reference beam 325 generating areadout beam 315 which illuminates display hologram 321. Displayhologram 321 and H.O.E. 323 are recorded in fixed position with respectto each other and therefore, a desired reticle hologram image is formed.Readout beam 315 is generated using H.O.E. 323 thus eliminating the needfor readout beam source 350. In this example, readout beam 315 is anangled beam pattern.

Positioning the reference beam directly aligned below display hologram321 and spaced apart from H.O.E. 323 allows for more compact assembly.In this example, bridge 312 extends from outer surfaces of the hologramsupport 311 to the outer surface of H.O.E. support 313 extending in arelatively downward projection. Reference beam source 24 can aligndirectly across from H.O.E. 323. In an example, reference beam 325 ishorizontally aligned with H.O.E. 323.

According to the present disclosure, the chassis assembly 300 isoperable for mounting onto a small arms weapon. The reference beamsource 324 is operable for generating a readout light beam 315 fromH.O.E. 323. The display hologram 321 is spaced apart from the H.O.E. 323to be illuminated by the readout light beam 315. Display hologram 321includes a target image recorded thereon. The target image is operableto display a perceived reticle image when illuminated by the readoutlight beam 315. The perceived image is visible at an apparent distancefrom the assembly 300. Accordingly, a user of the weapon will see avisible reticle, such as a cross hair image, a circle, or a visible dot,and use the hologram as a target or sight.

Display hologram 321 and H.O.E. 323 are fixed in near identical relativeposition to each other as when recorded. The H.O.E. 323 and the displayhologram 321 are fixed on chassis assembly 300. The H.O.E. 323 anddisplay hologram 321 can be positioned in a reflective image orientationas shown in FIG. 12. Alternatively, a transmission image orientation canalso be used wherein the direction of the light emitting from the lightsource is aligned with the direction of the H.O.E. and the readout beam.The present disclosure further provides for a base with an attachmentfor mounting to an upper surface or rail of a weapon.

The invention is not restricted to the illustrative examples andembodiments described above. The embodiments are not intended aslimitations on the scope of the invention. Methods, apparatus,compositions, and the like described herein are exemplary and notintended as limitations on the scope of the invention. Changes thereinand other uses will occur to those skilled in the art. The scope of theinvention is defined by the scope of the claims.

The invention claimed is:
 1. A compact weapon sight, comprising: ahousing having a base configured to mount to a weapon; a holographicoptical element (H.O.E.), the H.O.E. supported by the housing; a lightsource, the light source having a laser diode operable to emit a beam oflight at an output wavelength when energized, the laser diodeilluminating the H.O.E. when the laser diode is energized; a powersource operable to energize the laser diode; a temperature sensor forsensing a temperature of the laser diode; and an open loop wavelengthcontroller communicating with the temperature sensor, the temperaturesensor sensing and communicating the temperature of the laser diode tothe wavelength controller, the wavelength controller operable to controla current from the power source to the laser diode, the wavelengthcontroller adjusting the current based on a change in the temperaturesuch that the output wavelength is approximately the same as a desiredwavelength.
 2. The weapon sight in accordance with claim 1, wherein thetemperature sensor is a voltage sensor operable to measure a voltage ofthe laser diode during an off-period of a duty cycle.
 3. The weaponsight in accordance with claim 1, wherein the controller controls thecurrent in pulses such that the laser diode is energized for anon-period and is not energized for an off-period of a duty cycle.
 4. Theweapon sight in accordance with claim 1, wherein the laser diode is avertical-cavity surface emitting laser (VCSEL) diode.
 5. The weaponsight in accordance with claim 1, wherein the H.O.E. is a first H.O.E.,the sight further comprising a mirror, grating or second H.O.E., thelaser diode illuminating the mirror, grating or second H.O.E. and beingreflected or diffracted to illuminate the first H.O.E.
 6. The weaponsight in accordance with claim 5, wherein a position of the mirror,grating or second H.O.E. is adjustable.
 7. The weapon sight inaccordance with claim 1, wherein a beam of light that illuminates theH.O.E. is a non-collimated diverging beam of light.
 8. The weapon sightin accordance with claim 1, wherein the housing includes a chamberhaving a transparent portion, the laser diode being sealed within thechamber.
 9. The weapon sight in accordance with claim 8, furthercomprising: a carrier disposed in the chamber; and a tie rod at leastpartially disposed in the chamber, the carrier connected to the tie rodso as to be pivotable about an axis of the tie rod; the laser diodebeing disposed on the carrier.
 10. The weapon sight in accordance withclaim 9, further comprising: a frame supporting the H.O.E., the framebeing disposed outside the chamber and connected to a portion of the tierod extending outside the chamber; the frame and the carrier both beingrotationally fixed to the tie rod such that the laser diode and H.O.E.rotate together about the axis of the tie rod.
 11. The weapon sight inaccordance with claim 8, wherein the chamber is filled with nitrogen.12. The weapon sight in accordance with claim 1, further comprising: acarrier, the laser diode being disposed on the carrier; a framesupporting the H.O.E.; and a tie rod supported by the housing forrotation about an axis of the tie rod, the carrier and the frame bothbeing connected to and rotationally fixed to the tie rod so as to bepivotable about the axis of the tie rod such that the laser diode andH.O.E. rotate together relative to the housing about the axis of the tierod.
 13. The weapon sight in accordance with claim 12, furthercomprising: an elevation adjustment mechanism for adjusting therotational position of the carrier and frame relative to the housing,the elevation adjustment mechanism comprising; a shaft supported by thehousing and rotatable with respect to the housing; a first portion ofthe shaft having a first thread pitch, the first portion of the shaftthreaded to a first member, the first member fixedly connected to thehousing; and a second portion of the shaft having a second thread pitch,the second portion threaded to a movable second member, the secondmember being rotationally fixed with respect to the housing andlongitudinally movable with respect to the shaft, the second memberconnected to the carrier; wherein the first thread pitch is differentfrom the second thread pitch so as to provide for fine adjustment of thecarrier as the shaft rotates.
 14. The weapon sight in accordance withclaim 12, further comprising: a windage adjustment mechanism operable tomove the H.O.E. side to side with respect to the housing, the windageadjustment mechanism comprising; a shaft supported by the housing androtatable with respect to the housing; a first portion of the shafthaving a first thread pitch, the first portion of the shaft threaded toa first member, the first member fixedly connected to the housing; and asecond portion of the shaft having a second thread pitch, the secondportion threaded to a movable second member, the movable second memberbeing rotationally fixed with respect to the housing and longitudinallymovable with respect to the shaft, the second member connected to theH.O.E frame; wherein the first thread pitch is different from the secondthread pitch so as to provide for fine adjustment of the H.O.E. frame asthe shaft rotates.
 15. The weapon sight in accordance with claim 1,wherein: the beam of light from the laser diode is a readout light beamhaving a readout light beam phasefront; the H.O.E. is a display hologramthat reconstructs a reticle when illuminated by the readout light beam,the reconstructed reticle having a perceived distance; and the sightfurther comprising an adjustable feature operable for adjusting thereadout beam phasefront before illumination of the display hologram,wherein adjustment of the adjustable feature varies the perceiveddistance of the reticle image.
 16. The weapon sight in accordance withclaim 15, wherein the adjustable feature comprises a movable lenspositioned to modify the phasefront of the readout light beam prior toilluminating the display hologram.
 17. The weapon sight in accordancewith claim 15, further comprising a holographic optical element (H.O.E.)disposed in a position to be illuminated by the laser diode, the H.O.E.reconstructing an angled readout light beam when illuminated by thelaser diode, the angled readout light beam illuminating the displayhologram.
 18. The weapon sight in accordance with claim 1, wherein thelaser diode or the H.O.E. is horizontally and/or vertically adjustableby means of a multi-thread pitch adjustment assembly.
 19. The weaponsight in accordance with claim 1, wherein the base of the housing isintegral with a weapon.
 20. The weapon sight in accordance with claim 1,further comprising an accelerometer connected to the housing adapted toimprove battery life of the sight assembly.
 21. The weapon sight inaccordance with claim 1, wherein the weapon sight does not have athermoelectric cooler (TEC).
 22. A method of stabilizing an outputwavelength of a compact weapon sight, comprising: providing the housing,the holographic optical element (H.O.E.), the power source and the lightsource of claim 1; energizing the laser diode with the power source suchthat the laser diode emits a beam of light at an output wavelength;illuminating the H.O.E. with the beam of light; sensing a temperature ofthe laser diode with a temperature sensor; communicating a change in thetemperature of the laser diode to an open loop wavelength controller;controlling a current from the power source to the laser diode by usingthe controller; and adjusting the current based on the change in thetemperature by using the controller such that the output wavelength isapproximately the same as a desired wavelength.